Incorporating Ventricular Geometry into the Myocardial Work Index: A Proof-of-Concept Study

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Traditional mechanical work assessment (pressure-volume loop) is invasive.
• Myocardial Work Index (MWI) is a non-invasive alternative but ignores ventricular geometry.
• Ventricular geometry significantly influences myocardial load and wall stress (Laplace's law).

Purpose of the Study:

• To develop and evaluate a geometry-informed myocardial work framework.
• To provide a more physiologically representative estimate of mechanical energy expenditure.
• To compare the novel Tension-Adjusted Myocardial Work (TAMW) model with MWI.

Main Methods:

• Calculated mechanical work using a one-fiber LV model with Laplace-based geometric correction.
• Integrated fiber stress over strain to derive the TAMW model.
• Acquired strain (echocardiography), pressure, LV volumes, and geometry (cardiac MRI) data from two myocarditis patients.

Main Results:

• Conventional MWI showed a substantial performance gap (33.3%) between patients with different ventricular geometries.
• TAMW significantly reduced this discrepancy to 7.5%, indicating improved consistency.
• TAMW revealed distinct temporal distributions of instantaneous work compared to MWI, reflecting geometric influence.

Conclusions:

• The TAMW framework incorporates ventricular geometry for a more accurate myocardial work assessment.
• TAMW provides a more physiologically consistent reflection of myocardial effort across varying ventricular geometries.
• This geometry-informed approach enhances the clinical utility of non-invasive cardiac performance evaluation.